Conducting polymers obtained from quiescent and stirred solutions: Effects on the properties

Abstract

Poly(3,4-ethylenedioxythiophene), poly(N-methylpyr- role), and three-layered systems made of alternated layers of such two conducting polymers have been prepared by agitating the generation solution through a magnetic bar at a stirring speed of 400 rpm. The influence of these controlled dynamic conditions on both the electrochemical behavior and the superficial morphology has been examined. Results indicate that the increase in transport rate of reactants slightly favors the generation of more polymer weight at equal charge consumed. Consequently, the thickness of the materials prepared under stirring increases consider- ably with respect to those obtained from quiescent solutions, systems prepared using short (100 s) and large (300 s) polymerization times changing from nano- metric to submicrometric and from submicrometric to micrometric length-scales, respectively. Moreover, the porosity of PNMPy and PEDOT films also increases upon agitation. Thus, quiescent solutions produce compact and cavernous morphologies, respectively, for these materials, whereas the PNMPy and PEDOT obtained from agitated solutions are globular and spongy, respectively. Finally, the electroactivity, elec- trochemical stability, and electrical conductivity of the materials obtained from stirred solutions have been found to be significantly higher than those of the poly- mers prepared using quiescent solutions.